In large scale computing systems, it is often necessary to provide an operator with detailed information regarding the presence and status of mass storage devices. In order to provide such functionality, many storage solutions utilize a backplane with an integrated enclosure management device, referred to herein as an “enclosure management backplane.” In addition to performing other functions, an enclosure management backplane provides facilities for generating visual indicators based upon enclosure management data received from a connected host bus adapter (“HBA”). For instance, in some solutions, individual light-emitting diodes (“LEDs”) may be driven by an enclosure management backplane for displaying information regarding the activity, failure, rebuild status, and other information for each of the mass storage devices connected to the enclosure management backplane.
In order to provide these indicators, and other types of functionality, an enclosure management backplane typically provides connections for multiple mass storage devices, such as hard disk drives. The backplane also interfaces with an HBA and provides an interface through which the HBA may communicate with the mass storage devices. An enclosure management backplane also may receive and transmit enclosure management data to and from the HBA. Enclosure management data is any data relating to the provision of enclosure management services by a backplane.
Several different physical interfaces may be utilized to deliver enclosure management data between a HBA and an enclosure management backplane. For instance, some Serial Attached SCSI (“SAS”)-compatible HBAs are equipped with a serial general purpose input/output interface (“SGPIO”). Some Serial Advanced Technology Attachment (“SATA”)-compatible HBAs, on the other hand, utilize a control or management bus, such as the I2C bus from PHILIPS SEMICONDUCTORS, to exchange enclosure management data between the enclosure management backplane and the HBA. Some vendors have even implemented an enclosure management protocol based on the I2C bus for SAS HBAs.
The particular protocol utilized to transfer enclosure management data between the enclosure management backplane and the HBA may also vary from solution to solution. For instance, the Small Computer Systems Interface (“SCSI”) Accessed Fault-Tolerant Enclosures Interface Specification (“SAF-TE”) is typically utilized with SATA HBAs utilizing the I2C management bus. Alternatively, the SGPIO protocol may be utilized with a SAS HBA utilizing an SGPIO interface to exchange enclosure management information between a HBA and an enclosure management backplane. Other protocols, such as SCSI Enclosure Services-2 (“SES-2”), may also be utilized.
Most Integrated Drive Electronics (“IDE”) and SCSI mass storage devices are capable of driving an activity indicator directly. For instance, a light emitting diode (“LED”) may be connected directly to an activity signal provided by the device that is illuminated when the device is active. However, most SATA mass storage devices cannot drive an activity indicator directly.
Enclosure management protocols (e.g. SES-2, SGPIO, and SAF-TE) may also include data regarding the activity of the device. The drive activity information must be decoded by the enclosure management backplane to drive an activity indicator. Optionally, SATA devices may provide an activity indication through a pin on their interface (pin “P11”). Many SATA devices do not provide an activity signal on pin P11, however. All SAS devices provide activity information on a pin on their drive interface (pin P11). The signal provided is high when the drive is not connected and goes low when the drive is identified by the HBA. The signal toggles during drive activity. The enclosure management protocol utilized with SAS devices can also provide activity information for these types of mass storage devices.
Because some types of devices directly provide an activity indicator signal while others do not, it is difficult to provide an enclosure management backplane that supports drive activity indicators for different types of devices, such as SATA and SAS devices. It is with respect to these considerations and others that the present invention has been made.